1. Field of the Invention
The present invention relates to a system for performing proximal tibial osteotomies.
2. Description of the Related Art
Tibial osteotomies are performed to correct certain deformities. High tibial osteotomies (HTO) are indicated by early, medial joint-space narrowing, by early arthritis in patients who have had previous medial meniscectomy, or following rupture of the anterior cruciate ligament (ACL) in patients with pre-existing varus deformity, for example.
There are two schools of thought regarding osteotomy methods: the closing wedge method, and the opening wedge method. In the closing wedge method, removal of a bone wedge creates an angled gap in the bone. Part of the bone is left as a hinge at the apex of the angle. The hinge allows the gap to narrow, and the bone material on either side of the closed gap joins together.
In the opening wedge method, a cut is made across the bone. Part of the bone is left as a hinge, as in the closing wedge method. In contrast to the closing wedge method, however, the hinge allows the cut gap to open. The open wedge is filled with graft material.
The two methods are performed on opposite sides of the bone to give equivalent results. For example, when a given deformity would be corrected by performing the opening-wedge procedure on the medial side of a bone, an equivalent closing-wedge correction would be performed laterally.
The closing wedge method is the current standard, although several disadvantages are associated with the technique. The most significant disadvantages of the closing wedge method are: (i) disruption of the tibial-femoral joint; (ii) possible damage to neurovascular structures; and, (iii) disruption of the medial cortex, resulting in instability and nonunion between the upper and lower bone because of possible soft tissue interference. It is also difficult to compute the correct amount of bone to remove, and, therefore, several extra cuts may be required.
The opening wedge technique avoids or limits many of the disadvantages associated with the closing wedge method. Additionally, the medial, open-wedge HTO has the following advantages over the closed, lateral-wedge HTO: (i) speed; (ii) simplicity; (iii) ability to quickly change angle at any time during the procedure; and (iv) no fibular osteotomy is required. Nevertheless, only a few surgeons are currently using the opening wedge procedure. This is most likely due to a lack of proper instrumentation. Thus, a need exists for proper instrumentation to perform the opening wedge technique.